The present invention relates to novel mono and dicarbonyl derivatives of the compound 4-ethyl-1,3-dihydro-5-[4-(2-methyl-1H-imidazol-1-yl)benzoyl]-2H-imidazol-2 -one. This compound and its use as a cardiotonic agent are disclosed in U.S. Pat. No. 4,556,665, issued Dec. 3, 1985 to Paul W. Erhardt, et al. The compound is unique in that its cardiovascular profile is that of a selective inotropic agent. This in contradistinction to its analog the compound 4-ethyl-1,3-dihydro-5-[4-(1H-imidazol-1-yl)benzoyl]-2H-imidazol-2-one wherein the methyl group on the imidazole ring is missing. This latter compound whilst a potent cardiotonic agent also displays pronounced vascular effects.
In addition to a major biological differentiation between these 2 compounds a still greater difference occurs as to oral bioavailability. The latter compound, 4-ethyl-1,3-dihydro-5-[4-(1H-imidazol-1-yl)benzoyl]-2H-imidazolyl-2-one, that is the compound without the methyl group on the imidazole ring, is nearly 100% bioavailable on oral dosing. The pure inotrope 4-ethyl-1,3-dihydro-5-[4-(2-methyl-1H-imidazol-1-yl)benzoyl]-2H-imidazol-2 -one on the other hand is at best 20% bioavailable on oral dosing. The object of this invention is to derivatize this compound in such a manner as to make it, via oral dosing, at least bioavailable.